Business users and others manage data using storage control devices. A storage control device creates logical volumes in a storage area based on RAID (Redundant Array of Independent Disks). The logical volumes are provided to a host computer (hereinafter referred to as a host).
Because the amount of data used by a user increases day by day, the volume size set to match the current status becomes insufficient sooner or later. On the other hand, if the size is set excessively larger than the currently required size considering the increase of the data amount, there are many disk drives that are not immediately required and the cost increases.
Therefore, the technology of preparing virtual logical volumes and, in accordance with the actual use, allocating physical storage areas to the virtual logical volumes is proposed (Patent Literature 1).
[Patent Literature 1]
    U.S. Pat. No. 6,823,442